The representative compound 10c possessed potent high HDAC6 inhibitory activity (IC50 = 261 nM) and excellent HDAC6 selectivity (SI = 109), comparable to that of tubastatin A. In addition, 10c exhibited good antiproliferative activity against a panel of cancer cell lines with IC50 of 7.37–21.84 μM, better than tubastatin A (IC50 > 30 μM). This evidence concerns the gene HDAC6 and cancer.